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Diffstat (limited to 'scripts/basic/fixdep.c')
| -rw-r--r-- | scripts/basic/fixdep.c | 365 |
1 files changed, 365 insertions, 0 deletions
diff --git a/scripts/basic/fixdep.c b/scripts/basic/fixdep.c new file mode 100644 index 000000000..2328f9a64 --- /dev/null +++ b/scripts/basic/fixdep.c @@ -0,0 +1,365 @@ +/* + * "Optimize" a list of dependencies as spit out by gcc -MD + * for the kernel build + * =========================================================================== + * + * Author Kai Germaschewski + * Copyright 2002 by Kai Germaschewski <kai.germaschewski@gmx.de> + * + * This software may be used and distributed according to the terms + * of the GNU General Public License, incorporated herein by reference. + * + * + * Introduction: + * + * gcc produces a very nice and correct list of dependencies which + * tells make when to remake a file. + * + * To use this list as-is however has the drawback that virtually + * every file in the kernel includes autoconf.h. + * + * If the user re-runs make *config, autoconf.h will be + * regenerated. make notices that and will rebuild every file which + * includes autoconf.h, i.e. basically all files. This is extremely + * annoying if the user just changed CONFIG_HIS_DRIVER from n to m. + * + * So we play the same trick that "mkdep" played before. We replace + * the dependency on autoconf.h by a dependency on every config + * option which is mentioned in any of the listed prerequisites. + * + * kconfig populates a tree in include/config/ with an empty file + * for each config symbol and when the configuration is updated + * the files representing changed config options are touched + * which then let make pick up the changes and the files that use + * the config symbols are rebuilt. + * + * So if the user changes his CONFIG_HIS_DRIVER option, only the objects + * which depend on "include/config/HIS_DRIVER" will be rebuilt, + * so most likely only his driver ;-) + * + * The idea above dates, by the way, back to Michael E Chastain, AFAIK. + * + * So to get dependencies right, there are two issues: + * o if any of the files the compiler read changed, we need to rebuild + * o if the command line given to the compile the file changed, we + * better rebuild as well. + * + * The former is handled by using the -MD output, the later by saving + * the command line used to compile the old object and comparing it + * to the one we would now use. + * + * Again, also this idea is pretty old and has been discussed on + * kbuild-devel a long time ago. I don't have a sensibly working + * internet connection right now, so I rather don't mention names + * without double checking. + * + * This code here has been based partially based on mkdep.c, which + * says the following about its history: + * + * Copyright abandoned, Michael Chastain, <mailto:mec@shout.net>. + * This is a C version of syncdep.pl by Werner Almesberger. + * + * + * It is invoked as + * + * fixdep <depfile> <target> <cmdline> + * + * and will read the dependency file <depfile> + * + * The transformed dependency snipped is written to stdout. + * + * It first generates a line + * + * cmd_<target> = <cmdline> + * + * and then basically copies the .<target>.d file to stdout, in the + * process filtering out the dependency on autoconf.h and adding + * dependencies on include/config/MY_OPTION for every + * CONFIG_MY_OPTION encountered in any of the prerequisites. + * + * We don't even try to really parse the header files, but + * merely grep, i.e. if CONFIG_FOO is mentioned in a comment, it will + * be picked up as well. It's not a problem with respect to + * correctness, since that can only give too many dependencies, thus + * we cannot miss a rebuild. Since people tend to not mention totally + * unrelated CONFIG_ options all over the place, it's not an + * efficiency problem either. + * + * (Note: it'd be easy to port over the complete mkdep state machine, + * but I don't think the added complexity is worth it) + */ + +#include <sys/types.h> +#include <sys/stat.h> +#include <unistd.h> +#include <fcntl.h> +#include <string.h> +#include <stdarg.h> +#include <stdlib.h> +#include <stdio.h> +#include <ctype.h> + +static void usage(void) +{ + fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n"); + exit(1); +} + +struct item { + struct item *next; + unsigned int len; + unsigned int hash; + char name[]; +}; + +#define HASHSZ 256 +static struct item *hashtab[HASHSZ]; + +static unsigned int strhash(const char *str, unsigned int sz) +{ + /* fnv32 hash */ + unsigned int i, hash = 2166136261U; + + for (i = 0; i < sz; i++) + hash = (hash ^ str[i]) * 0x01000193; + return hash; +} + +/* + * Lookup a value in the configuration string. + */ +static int is_defined_config(const char *name, int len, unsigned int hash) +{ + struct item *aux; + + for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) { + if (aux->hash == hash && aux->len == len && + memcmp(aux->name, name, len) == 0) + return 1; + } + return 0; +} + +/* + * Add a new value to the configuration string. + */ +static void define_config(const char *name, int len, unsigned int hash) +{ + struct item *aux = malloc(sizeof(*aux) + len); + + if (!aux) { + perror("fixdep:malloc"); + exit(1); + } + memcpy(aux->name, name, len); + aux->len = len; + aux->hash = hash; + aux->next = hashtab[hash % HASHSZ]; + hashtab[hash % HASHSZ] = aux; +} + +/* + * Record the use of a CONFIG_* word. + */ +static void use_config(const char *m, int slen) +{ + unsigned int hash = strhash(m, slen); + + if (is_defined_config(m, slen, hash)) + return; + + define_config(m, slen, hash); + /* Print out a dependency path from a symbol name. */ + printf(" $(wildcard include/config/%.*s) \\\n", slen, m); +} + +/* test if s ends in sub */ +static int str_ends_with(const char *s, int slen, const char *sub) +{ + int sublen = strlen(sub); + + if (sublen > slen) + return 0; + + return !memcmp(s + slen - sublen, sub, sublen); +} + +static void parse_config_file(const char *p) +{ + const char *q, *r; + const char *start = p; + + while ((p = strstr(p, "CONFIG_"))) { + if (p > start && (isalnum(p[-1]) || p[-1] == '_')) { + p += 7; + continue; + } + p += 7; + q = p; + while (isalnum(*q) || *q == '_') + q++; + if (str_ends_with(p, q - p, "_MODULE")) + r = q - 7; + else + r = q; + if (r > p) + use_config(p, r - p); + p = q; + } +} + +static void *read_file(const char *filename) +{ + struct stat st; + int fd; + char *buf; + + fd = open(filename, O_RDONLY); + if (fd < 0) { + fprintf(stderr, "fixdep: error opening file: "); + perror(filename); + exit(2); + } + if (fstat(fd, &st) < 0) { + fprintf(stderr, "fixdep: error fstat'ing file: "); + perror(filename); + exit(2); + } + buf = malloc(st.st_size + 1); + if (!buf) { + perror("fixdep: malloc"); + exit(2); + } + if (read(fd, buf, st.st_size) != st.st_size) { + perror("fixdep: read"); + exit(2); + } + buf[st.st_size] = '\0'; + close(fd); + + return buf; +} + +/* Ignore certain dependencies */ +static int is_ignored_file(const char *s, int len) +{ + return str_ends_with(s, len, "include/generated/autoconf.h") || + str_ends_with(s, len, "include/generated/autoksyms.h"); +} + +/* + * Important: The below generated source_foo.o and deps_foo.o variable + * assignments are parsed not only by make, but also by the rather simple + * parser in scripts/mod/sumversion.c. + */ +static void parse_dep_file(char *m, const char *target) +{ + char *p; + int is_last, is_target; + int saw_any_target = 0; + int is_first_dep = 0; + void *buf; + + while (1) { + /* Skip any "white space" */ + while (*m == ' ' || *m == '\\' || *m == '\n') + m++; + + if (!*m) + break; + + /* Find next "white space" */ + p = m; + while (*p && *p != ' ' && *p != '\\' && *p != '\n') + p++; + is_last = (*p == '\0'); + /* Is the token we found a target name? */ + is_target = (*(p-1) == ':'); + /* Don't write any target names into the dependency file */ + if (is_target) { + /* The /next/ file is the first dependency */ + is_first_dep = 1; + } else if (!is_ignored_file(m, p - m)) { + *p = '\0'; + + /* + * Do not list the source file as dependency, so that + * kbuild is not confused if a .c file is rewritten + * into .S or vice versa. Storing it in source_* is + * needed for modpost to compute srcversions. + */ + if (is_first_dep) { + /* + * If processing the concatenation of multiple + * dependency files, only process the first + * target name, which will be the original + * source name, and ignore any other target + * names, which will be intermediate temporary + * files. + */ + if (!saw_any_target) { + saw_any_target = 1; + printf("source_%s := %s\n\n", + target, m); + printf("deps_%s := \\\n", target); + } + is_first_dep = 0; + } else { + printf(" %s \\\n", m); + } + + buf = read_file(m); + parse_config_file(buf); + free(buf); + } + + if (is_last) + break; + + /* + * Start searching for next token immediately after the first + * "whitespace" character that follows this token. + */ + m = p + 1; + } + + if (!saw_any_target) { + fprintf(stderr, "fixdep: parse error; no targets found\n"); + exit(1); + } + + printf("\n%s: $(deps_%s)\n\n", target, target); + printf("$(deps_%s):\n", target); +} + +int main(int argc, char *argv[]) +{ + const char *depfile, *target, *cmdline; + void *buf; + + if (argc != 4) + usage(); + + depfile = argv[1]; + target = argv[2]; + cmdline = argv[3]; + + printf("cmd_%s := %s\n\n", target, cmdline); + + buf = read_file(depfile); + parse_dep_file(buf, target); + free(buf); + + fflush(stdout); + + /* + * In the intended usage, the stdout is redirected to .*.cmd files. + * Call ferror() to catch errors such as "No space left on device". + */ + if (ferror(stdout)) { + fprintf(stderr, "fixdep: not all data was written to the output\n"); + exit(1); + } + + return 0; +} |